TOI10: ไปโรงเรียน (Go to School)

#include <bits/stdc++.h>

using namespace std;

using lli = long long;
const lli zero = 0;
lli dp[60][60];
bool dog[60][60];

int main(){

    int m, n;
    scanf("%d%d", &m, &n);

    int d;
    scanf("%d", &d);

    for(int i=1;i<=d;i++){
        int I, J;
        scanf("%d%d", &J, &I);
        dog[I][J] = true;
    }

    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(dog[i][j]) continue;
            if(i == 1 and j == 1) dp[i][j] = 1;
            else if(i == 1) dp[i][j] = dp[i][j-1];
            else if(j == 1) dp[i][j] = dp[i-1][j];
            else dp[i][j] = dp[i-1][j] + dp[i][j-1];
        }
    }

    printf("%lld", dp[n][m]);

    return 0;
}