#include <stdio.h>
unsigned long long cbjabs(long long a){
    if(a < 0){
        char x[64] = { 0 };
        unsigned long long t;
        sprintf(x, "%lld", a);
        sscanf(x + 1, "%llu", &t);
        return t;
    }
    else{
        return a;
    }

}
int main(){
    long long a, b;
    unsigned long long a0, b0;
    char s1 = 0, s2 = 0;
    scanf("%lld%lld", &a, &b);
    if(a < 0){
        s1 = 1;
        a0 = -a;//cbjabs(a);
    }
    else{
        a0 = a;
    }
    if(b < 0){
        s2 = 1;
        b0 = -b;//cbjabs(b);
    }
    else{
        b0 = b;
    }
    if(s1 == 1 && s2 == 1){
        //负 负
        if((a0 + b0 > 9223372036854775808ull) || ((a0 == 9223372036854775808ull) && (b0 == 9223372036854775808ull))){
            puts("NO!");
        }
        else{
            printf("%lld\n", a + b);
        }
    }
    else if(s1 == 0 && s2 == 1){
        //正 负
        printf("%lld\n", a + b);
    }
    else if(s1 == 1 && s2 == 0){
        //负 正
        printf("%lld\n", a + b);
    }
    else{
        //正 正
        if(a0 + b0 > 9223372036854775807ull){
            puts("PO!");
        }
        else{
            printf("%lld\n", a + b);
        }
    }

    return 0;
}