/in/foo.cc:5:1: error: expected initializer before 'int'
 int i,k;
 ^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:13:16: error: 'M' was not declared in this scope
         memset(M, '0', sizeof(M));
                ^
/in/foo.cc:13:33: error: 'memset' was not declared in this scope
         memset(M, '0', sizeof(M));
                                 ^
/in/foo.cc:14:13: error: 'i' was not declared in this scope
         for(i=0;i<n;i++)
             ^
/in/foo.cc:17:21: error: 'k' was not declared in this scope
                 for(k=x;k<=y;k++)M[k]='1';
                     ^
/in/foo.cc:20:13: error: 'i' was not declared in this scope
         for(i=0;i<m;i++)
             ^