Language: C++

#include<bits/stdc++.h>
using namespace std;

///Author:Refat(BSMRSTU)///

#define ll long long
#define ull unsigned long long
#define ff first#include<bits/stdc++.h>
using namespace std;

///Author:Refat(BSMRSTU)///

#define ll long long
#define ull unsigned long long
#define ff first
#define ss second
#define pb push_back
#define vi vector<int>
#define pii pair<int,int>
#define pil pair<int,ll>
const int N = 1e5 + 5;
const int M = 1e9 + 7;
const double pi=2*acos(0.0);
const double esp=1e-9;
int Set(int N,int pos) {
    return N=N | (1<<pos);
}
int reset(int N,int pos) {
    return N= N & ~(1<<pos);
}
bool check(int N,int pos) {
    return (bool)(N & (1<<pos));
}
int main() {
    /// freopen("input.txt","r",stdin);
    /// freopen("output.txt","w",stdout);
    int test=1;
    ///scanf("%d",&test);
    for(int cs=1; cs<=test; cs++) {
       int n,m;
       scanf("%d %d",&n,&m);
       if((n>=1&&n<=9)&&(m>=1&&m<=9)){
        printf("%d\n",n*m);
       }
       else{
        printf("-1\n");
       }
    }
    return 0;
}


#define ss second
#define pb push_back
#define vi vector<int>
#define pii pair<int,int>
#define pil pair<int,ll>
const int N = 1e#include<bits/stdc++.h>
using namespace std;

///Author:Refat(BSMRSTU)///

#define ll long long
#define ull unsigned long long
#define ff first
#define ss second
#define pb push_back
#define vi vector<int>
#define pii pair<int,int>
#define pil pair<int,ll>
const int N = 1e5 + 5;
const int M = 1e9 + 7;
const double pi=2*acos(0.0);
const double esp=1e-9;
int Set(int N,int pos) {
    return N=N | (1<<pos);
}
int reset(int N,int pos) {
    return N= N & ~(1<<pos);
}
bool check(int N,int pos) {
    return (bool)(N & (1<<pos));
}
int main() {
    /// freopen("input.txt","r",stdin);
    /// freopen("output.txt","w",stdout);
    int test=1;
    ///scanf("%d",&test);
    for(int cs=1; cs<=test; cs++) {
       int n,m;
       scanf("%d %d",&n,&m);
       if((n>=1&&n<=9)&&(m>=1&&m<=9)){
        printf("%d\n",n*m);
       }
       else{
        printf("-1\n");
       }
    }
    return 0;
}

5 + 5;
const int M = 1e9 + 7;
const double pi=2*acos(0.0);
const double esp=1e-9;
int Set(int N,int pos) {
    return N=N | (1<<pos);
}
int reset(int N,int pos) {
    return N= N & ~(1<<pos);
}
bool check(int N,int pos) {
    return (bool)(N & (1<<pos));
}
int main() {
    /// freopen("input.txt","r",stdin);
    /// freopen("output.txt","w",stdout);
    int test=1;
    ///scanf("%d",&test);
    for(int cs=1; cs<=test; cs++) {
       int n,m;
       scanf("%d %d",&n,&m);
       if((n>=1&&m<=9)){
        printf("%d\n",n*m);
       }
       else{
        printf("-1\n");
       }
    }
    return 0;
}



Compiler output:
a.cc:15:9: warning: "ff" redefined
   15 | #define ff first
      |         ^~
a.cc:8:9: note: this is the location of the previous definition
    8 | #define ff first#include<bits/stdc++.h>
      |         ^~
a.cc:58:15: error: exponent has no digits
   58 | const int N = 1e#include<bits/stdc++.h>
      |               ^~
a.cc:58:17: error: stray '#' in program
   58 | const int N = 1e#include<bits/stdc++.h>
      |                 ^
a.cc:58:11: error: redefinition of 'const int N'
   58 | const int N = 1e#include<bits/stdc++.h>
      |           ^
a.cc:21:11: note: 'const int N' previously defined here
   21 | const int N = 1e5 + 5;
      |           ^
a.cc:71:11: error: redefinition of 'const int N'
   71 | const int N = 1e5 + 5;
      |           ^
a.cc:21:11: note: 'const int N' previously defined here
   21 | const int N = 1e5 + 5;
      |           ^
a.cc:72:11: error: redefinition of 'const int M'
   72 | const int M = 1e9 + 7;
      |           ^
a.cc:22:11: note: 'const int M' previously defined here
   22 | const int M = 1e9 + 7;
      |           ^
a.cc:73:14: error: redefinition of 'const double pi'
   73 | const double pi=2*acos(0.0);
      |              ^~
a.cc:23:14: note: 'const double pi' previously defined here
   23 | const double pi=2*acos(0.0);
      |              ^~
a.cc:74:14: error: redefinition of 'const double esp'
   74 | const double esp=1e-9;
      |              ^~~
a.cc:24:14: note: 'const double esp' previously defined here
   24 | const double esp=1e-9;
      |              ^~~
a.cc:75:5: error: redefinition of 'int Set(int, int)'
   75 | int Set(int N,int pos) {
      |     ^~~
a.cc:25:5: note: 'int Set(int, int)' previously defined here
   25 | int Set(int N,int pos) {
      |     ^~~
a.cc:78:5: error: redefinition of 'int reset(int, int)'
   78 | int reset(int N,int pos) {
      |     ^~~~~
a.cc:28:5: note: 'int reset(int, int)' previously defined here
   28 | int reset(int N,int pos) {
      |     ^~~~~
a.cc:81:6: error: redefinition of 'bool check(int, int)'
   81 | bool check(int N,int pos) {
      |      ^~~~~
a.cc:31:6: note: 'bool check(int, int)' previously defined here
   31 | bool check(int N,int pos) {
      |      ^~~~~
a.cc:84:5: error: redefinition of 'int main()'
   84 | int main() {
      |     ^~~~
a.cc:34:5: note: 'int main()' previously defined here
   34 | int main() {
      |     ^~~~
a.cc:102:1: error: expected unqualified-id before numeric constant
  102 | 5 + 5;
      | ^
a.cc:103:11: error: redefinition of 'const int M'
  103 | const int M = 1e9 + 7;
      |           ^
a.cc:22:11: note: 'const int M' previously defined here
   22 | const int M = 1e9 + 7;
      |           ^
a.cc:104:14: error: redefinition of 'const double pi'
  104 | const double pi=2*acos(0.0);
      |              ^~
a.cc:23:14: note: 'const double pi' previously defined here
   23 | const double pi=2*acos(0.0);
      |              ^~
a.cc:105:14: error: redefinition of 'const double esp'
  105 | const double esp=1e-9;
      |              ^~~
a.cc:24:14: note: 'const double esp' previously defined here
   24 | const double esp=1e-9;
      |              ^~~
a.cc:106:5: error: redefinition of 'int Set(int, int)'
  106 | int Set(int N,int pos) {
      |     ^~~
a.cc:25:5: note: 'int Set(int, int)' previously defined here
   25 | int Set(int N,int pos) {
      |     ^~~
a.cc:109:5: error: redefinition of 'int reset(int, int)'
  109 | int reset(int N,int pos) {
      |     ^~~~~
a.cc:28:5: note: 'int reset(int, int)' previously defined here
   28 | int reset(int N,int pos) {
      |     ^~~~~
a.cc:112:6: error: redefinition of 'bool check(int, int)'
  112 | bool check(int N,int pos) {
      |      ^~~~~
a.cc:31:6: note: 'bool check(int, int)' previously defined here
   31 | bool check(int N,int pos) {
      |      ^~~~~
a.cc:115:5: error: redefinition of 'int main()'
  115 | int main() {
      |     ^~~~
a.cc:34:5: note: 'int main()' previously defined here
   34 | int main() {
      |     ^~~~