#include <stdio.h>
#include <math.h>
#include <ctype.h>
#include <math.h>
int is_int_string(const char *s) {
    int i = 0;
    if (s[0] == '') return 0;
    if (s[i] == '+' || s[i] == '-')
    i++;
    if (!isdigit((unsigned char)s[i]))
    return 0;
    for (: s[i] != ''; i++) {
        if (!isdigit((unsigned char)s[i]))
        return 0;
    }return 1;
}
int main (void) {
    int n;
    char sx1[16], sy1[16], sx2[16], sy2[16];
    if (scanf("%d", &n) != 1) {
        printf("Invalid input");
        return 0;
    }
    for(int i = 0; i < n; i++) {
        if (scanf("%15s %15s %15s %15s", sx1, sy1. sx2, sy2) != 4) {
            printf("invalid input");
            return 0;
        }
        if (!is_int_string(sx1) || !is_int_string(sy1) || !is_int_string(sx2) || !is_int_string(sy2)) {
            printf("Invalid input");
            return 0;
    }
    int x1, y1, x2, y2;
    sscanf(sx1, "%d", &x1);
    sscanf(sy1, "%d", &y1);
    sscanf(sx2, "%d", &x2);
    sscanf(sy2, "%d", &y2);
    
    double dx = x2 - x1;
    double dy = y2 - y1;
    double dist = sqrt(dx * dx + dy * dy);
    printf(".2f",dist);
    
}
return 0;
}