Codeforces 1248 #Codeforces

1248C.cpp

#include <bits/stdc++.h>
#define ll long long
#define Android ios::sync_with_stdio(false), cin.tie(NULL)
using namespace std;

const ll inf=0x3f3f3f3f3f3f3f3f;
const ll mod = 1e9 + 7;

ll fib(int n){
    int a = 1, b = 1, c;
    if(n <= 1) return 1;
    for(int i=2; i<=n; i++){
        c = (a + b) % mod;
        a = b, b = c;
    }
    return c;
}

void solve(){
    int n, m;
    cin >> n >> m;
    cout << (fib(n) + fib(m) - 1) % mod * 2 % mod << '\n';
}

signed main(){
    Android;
    solve();
}