Language: C++

#include <iostream>
#include <string>
using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}

Compiler output:
a.cc: In function 'int main()':
a.cc:3:337: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
    3 | using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}
      |                                                                                                                                                                                                                                                                                                                                                 ^~~
      |                                                                                                                                                                                                                                                                                                                                                 |
      |                                                                                                                                                                                                                                                                                                                                                 const char*
a.cc:3:354: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
    3 | using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}
      |                                                                                                                                                                                                                                                                                                                                                                  ^~~
      |                                                                                                                                                                                                                                                                                                                                                                  |
      |                                                                                                                                                                                                                                                                                                                                                                  const char*
a.cc:3:371: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
    3 | using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}
      |                                                                                                                                                                                                                                                                                                                                                                                   ^~~
      |                                                                                                                                                                                                                                                                                                                                                                                   |
      |                                                                                                                                                                                                                                                                                                                                                                                   const char*
a.cc:3:388: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
    3 | using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}
      |                                                                                                                                                                                                                                                                                                                                                                                                    ^~~
      |                                                                                                                                                                                                                                                                                                                                                                                                    |
      |                                                                                                                                                                                                                                                                                                                                                                                                    const char*
a.cc:3:414: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
    3 | using namespace std;int main(){int b[5][4];int sx,sy;int x,y;string line;while(true){for(int i=0;i<20;i++)b[i%5][i/5]=0;sx=sy=-1;for(y=0;y<8;y++){if (!(cin>>line))break;for(x=0;x<8;x++){if (line[x]=='1'){if (sy==-1){sx=x-1;sy=y;}b[x-sx][y-sy] = 1;}}}if (y<8)break;char a;if(b[2][0]&&b[1][1]&&b[2][1])a='A';if(b[1][3])a='B';if(b[4][0])a="C";if(b[0][2])a="D";if(b[3][1])a="E";if(b[2][2])a="F";if(b[0][1]&&b[2][0])a="G";cout<<a<<endl;}}
      |                                                                                                                                                                                                                                                                                                                                                                                                                              ^~~
      |                                                                                                                                                                                                                                                                                                                                                                                                                              |
      |                                                                                                                                                                                                                                                                                                                                                                                                                              const char*