#include<stdio.h>
#include<string.h>


int main(){
    char inp[512];
    int i, j, len, is_constant, point, expo, plus, minus, after_e;

start:


    i = 0;
    j = 0;
    len = 0;
    is_constant = 1;
    point = 0;
    expo = 0;
    plus = 0;
    minus = 0;
    after_e = 0;

    printf("Enter Constant: ");
    scanf("%[^\n]s", inp);

    len = strlen(inp);

    for(i = 0; i < len; i++){

        // Check for digits and .
        if(!((inp[i] >= '0' && inp[i] <= '9') || inp[i] == '.' || inp[i] == '-' || inp[i] == '+' || inp[i] == 'E' || inp[i] == 'e')){
            is_constant = 0;
            break;
        }

        // Check for Multiple .
        if(inp[i] == '.'){
            point++;
            if(point > 1){
                is_constant = 0;
                break;
            }
        }

        if(inp[i] == 'E' || inp[i] == 'e'){
            expo++;
            if(expo > 1){
                is_constant = 0;
                break;
            }
        }

        if(inp[i] == '+'){
            plus++;
            if(plus > 1){
                is_constant = 0;
                break;
            }
        }

        if(inp[i] == '-'){
            minus++;
            if(minus > 1){
                is_constant = 0;
                break;
            }
        }
    }

    if(is_constant == 1 && expo == 1){
        for(i = 0; i < len; i++){
            // Plus Minus out of E
            if(inp[i] == '-' || inp[i] == '+'){
                is_constant = 0;
                break;
            }

            if(inp[i] == 'E' || inp[i] == 'e'){
                // More Checks
                for(j = i; j < len; j++){
                    after_e++;
                }
            }
        }

        if(expo > 0 && after_e == 1){
            is_constant = 0;
        }
    }


    if(is_constant == 1 && len > 0){
        printf("Constant\n\n");
    }else{
        printf("Not a Constant\n\n");
    }

    fflush(stdin);
    goto start;


    return 0;
}