样例可以过，但是全部 RE 了，求助/kel

#include <bits/stdc++.h>
#define int __int128
#define ll long long
using namespace std;
int n, m, l, P;
ll t1, t2, t3;

int getinv(int x) {
    if(x == 1) return 1;
    return (P - (P / x) * getinv(P % x) % P) % P;
}

signed main() {
    scanf("%lld%lld%lld", &t1, &t2, &t3);
    n = t1, m = t2, l = t3; P = n + 1;
    int ans = l * getinv(m << 1) % P;
    printf("%lld\n", (ll)ans);
    return 0;
}