Language: C

d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'd' [-Wimplicit-int]
main.c:1:6: error: type defaults to 'int' in declaration of 'e' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |      ^
main.c:1:11: error: type defaults to 'int' in declaration of 'f' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |           ^
main.c:1:13: error: type defaults to 'int' in declaration of 'k' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |             ^
main.c:1:26: error: return type defaults to 'int' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                          ^
main.c:1:140: error: return type defaults to 'int' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                                                                                                                                            ^
main.c: In function 'y':
main.c:1:140: error: type of 'o' defaults to 'int' [-Wimplicit-int]
main.c:1:140: error: type of 'n' defaults to 'int' [-Wimplicit-int]
main.c:1:140: error: type of 'i' defaults to 'int' [-Wimplicit-int]
main.c:1:140: error: type of 'j' defaults to 'int' [-Wimplicit-int]
main.c:1:185: error: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                                                                                                                                                                                         ^~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'puts'
  +++ |+#include <stdio.h>
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
main.c:1:240: error: expected expression before ']' token
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                                                                                                                                                                                                                                                ^
main.c: At top level:
main.c:1:364: error: return type defaults to 'int' [-Wimplicit-int]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                                                                                                                                                                                                                                                                                                                                                                            ^~~~
main.c: In function 'main':
main.c:1:376: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | d[4],e[9],f,k;char s[30];z(){int b,c,a=e[f++];a>9?s[k++]=40,b=z(),s[k++]=a,c=z(),s[k++]=41,a=a-43?a-45?b*c:b-c:b+c:(s[k++]=a+48);return a;}y(o,n,i,j){if(i==7){f=k=0;if(z()==10){s[k]=0;puts(s);return 1;}return 0;}if(o)for(;j--;){e[i]="+-*"[];if(y(o-1,n+1,i+1,3))return 1;}if(n|i==6)for(j=4;j--;)if(e[i]=d[j]){d[j]=0;if(y(o,n-1,i+1,3))return 1;d[j]=e[i];}return 0;}main(){for(;scanf("%d%d%d%d",d,d+1,d+2,d+3),f=*d;)y(3,0,0,3)||puts("0");}
      |                                                                                                                                                                                                                                                                                                                                                                                        ^~~~~
main.c:1:376: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:376: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
main.c:1:376: note: include '<stdio.h>' or provide a declaration of 'scanf'