The question is simple. So is my code. See below It gets AC in VC++2000.
But why does it get WA#1 in gcc4.7.2 and gcc4.7.2-c++11, until I replace the while-scanf loop with the commented while-cin loop?

Thanks.

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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <vector>
int main()
{
    std::vector<long long> v;
    long long t;
    while (std::scanf("%lld", &t) != EOF) {
    // while (std::cin >> t) {
        v.push_back(t);
    }
    for (int i=v.size()-1; i>=0; --i) {
        printf("%.5f\n", sqrt((double)(v[i])));
    }
}