Escape<Unique Path DP>

#include <bits/stdc++.h>
using namespace std;
int main(){
    int M=1e9+7;
    int n,m;
    scanf("%d%d",&n,&m);
    int a[n][m];
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            scanf("%d",&a[i][j]);
        }
    }
    long long b[n][m];
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            if(a[i][j]==1){
                b[i][j]=0;
            }
            else if(i==0&&j==0) b[i][j]=1;
            else if(i==0) b[i][j]=b[i][j-1];
            else if(j==0) b[i][j]=b[i-1][j];
            else b[i][j]=(b[i-1][j]+b[i][j-1])%M;
        }
    }
    printf("%lld",b[n-1][m-1]);
}