View Compilation Error

0_0_23428989_18483.cpp: In function 'void solve()':
0_0_23428989_18483.cpp:25:25: error: 'n' was not declared in this scope
     for (int i = 0; i < n; ++i)
                         ^
0_0_23428989_18483.cpp:40:25: error: 'n' was not declared in this scope
     for (int i = 0; i < n; ++i)
                         ^
0_0_23428989_18483.cpp:47:19: error: 'n' was not declared in this scope
     for(int i=0;i<n;i++)
                   ^
0_0_23428989_18483.cpp: In function 'int main()':
0_0_23428989_18483.cpp:60:30: error: 'n' was not declared in this scope
     while (scanf("%d%d%d%d",&n,&m,&x,&y)!=EOF)
                              ^