Mouse and corns (DP)

#include<bits/stdc++.h>
using namespace std;
long long n,m,a[102][102],s[102][102];
void f(int i,int j){
    if(i==n and j==1){
        return;
    }
    if(s[i][j-1]>=s[i+1][j] and j-1>0){
        f(i,j-1);
        cout<<"R";
    }
    else{
        f(i+1,j);
        cout<<"F";
    }
}
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>a[i][j];
        }
    }
    for(int i=n;i>0;i--){
        for(int j=1;j<=m;j++){
            s[i][j]=max(s[i+1][j],s[i][j-1])+a[i][j];
        }
    }
    f(1,m);
    cout<<endl;
    return 0;
}