View Compilation Error

0_0_22130016_31376.cpp: In function 'int main()':
0_0_22130016_31376.cpp:21:23: error: 'n' was not declared in this scope
         scanf("%d%d",&n,&m);
                       ^
0_0_22130016_31376.cpp:21:26: error: 'm' was not declared in this scope
         scanf("%d%d",&n,&m);
                          ^
0_0_22130016_31376.cpp:40:5: error: return-statement with no value, in function returning 'int' [-fpermissive]
     return ;
     ^