#include <stdio.h>

int main() {
    float sign,sum,deno,term;
    sign=sum=1,deno=2;
    for(;deno<=100;deno++)
    {
        sign=(-1)*sign;
        term=sign/deno;
        sum=sum+term;
    }
    printf("1-1/2+1/3-1/4+...+1/99-1/100=%f",sum);
    return 0;
}