UVa 1388 - Graveyard

/*ch1, 例题4*/#include <cstdio>#include <algorithm>#include <cmath>using namespace std;int main(){    #ifndef ONLINE_JUDGE    freopen("in.txt", "r", stdin);    #endif // ONLINE_JUDGE    int n, m;    while(scanf("%d%d", &n, &m) == 2) {        double v, sum = 0.0;        for(int i=1; i<n; i++) {            v = (double)i * (n+m) / n;            sum += abs(v - floor(v+0.5));        }        printf("%.4lf\n", sum*10000/(n+m));    }    return 0;}