#include <stdio.h>
double prob(int n){
    // This computes the probability that 
    // there is no two persons with the same Bday
    int i;
    double prob = 1;
    for (i=0;i<n;i++){
        prob *= (365.0-i)/365.0;    
    }
    return 1.0 - prob;    
}


int main(int argc, char **argv){

    int n;
    n=1;
    for(n=1;prob(n)<0.5;n++);
    printf("for n=%d prob=%f\n",n,prob(n));

    for(n=1;prob(n)<0.75;n++);
    printf("for n=%d prob=%f\n",n,prob(n));
}